BBC Learning English. I'm Neil.

And I'm Sam.

What do shopping with a credit card,

finding love through internet

dating and waiting for the traffic

lights to change have in common?

Hmmm, they all involve computers?

Good guess, Sam! But how exactly

do those computers work?

The answer is that they all

use algorithms - sets of

mathematical instructions

which find solutions to problems.

Although they are often hidden,

algorithms are all around us.

From mobile phone maps to

home delivery pizza, they

play a big part of modern

life. And they're the

topic of this programme.

A simple way to think of

algorithms is as recipes.

To make pancakes you mix flour,

eggs and milk, then melt

butter in a frying pan

and so on. Computers do

this in more a complicated

way by repeating mathematical

equations over and over again.

Equations are mathematical

sentences showing how two

things are equal. They're

similar to algorithms and

the most famous scientific

equation of all, Einstein's

E=MC2, can be thought of as

a three-part algorithm.

But before my brain gets

squashed by all this maths,

I have a quiz question for

you, Sam. As you know,

Einstein's famous equation

is E=MC2 - but what does the

'E' stand for? Is it:

a) electricity? b) energy?

or c) everything?

I'm tempted to say 'E' is

for 'everything' but I

reckon I know the answer:

b - 'E' stands for 'energy'.

OK, Sam, we'll find out if

you're right later

in the programme.

With all this talk of

computers, you might think

algorithms are a new idea.

In fact, they've been

around since Babylonian times,

around 4,000 years ago.

And their use today can be

controversial. Some algorithms

used in internet search engines

have been accused

of racial prejudice.

Ramesh Srinivasan is Professor

of Information Studies at the

University of California.

Here's what he said when asked

what the word 'algorithm'

actually means by BBC World

Service's programme, The Forum:

My understanding of the term

'algorithm' is that it's not

necessarily the bogyman, or

its not necessarily something

that is, you know, inscrutable

or mysterious to all people -

it's the set of instructions

that you write in some

mathematical form or in

some software code - so it's

the repeated set of

instructions that are

sequenced, that are used

and applied to answer a

question or resolve a

problem - it's a simple as

that, actually.

Some think that algorithms

have been controversial,

but Professor Srinivasan

says they are not necessarily

the bogyman. The bogyman

refers to something people

call 'bad' or 'evil' to

make other people afraid.

Professor Srinivasan thinks

algorithms are neither evil

nor inscrutable - not

showing emotions or thoughts

and therefore very difficult

to understand.

Still, it can be difficult

to understand exactly what

algorithms are, especially

when there are many different

types of them. So, let's

take an example.

It's autumn and we want to

collect all the apples from

our orchard and divide them

into three groups - big, medium

and small. One method is to

collect all the apples together

and compare their sizes.

But doing this would take hours!

It's much easier to first

collect the apples from only

one tree - divide those into

big, medium or small - and

then repeat the process for

the other trees, one by one.

That's basically what

algorithms do - they find

the most efficient way to

get things done, or in other

words, get the best results

in the quickest time.

Mathematics professor Ian Stewart

agrees. Listen as he explains

how the algorithm called

'bubble sort' works to BBC

World Service's programme,

The Forum:

Think of when your computer

is sorting emails by date and

maybe you've got 500 emails

and it sorts them by date in

a flash. Now it doesn't use

bubble sort, but it does

use a sorting method and if

you tried to do that by

hand it would take you a

very long time, whatever

method you used.

Professor Stewart describes

how algorithms sort emails.

'To sort' is a verb meaning

to group together things

which share similarities.

Just like grouping the

apples by size, sorting

hundreds of emails by hand

would take a long time.

But using algorithms,

computers do it in a flash -

very quickly or suddenly.

That phrase - in a flash -

reminds me of

how Albert Einstein

came up with his famous

equation, E=MC2.

And that reminds me of your

quiz question. You asked

about the 'E' in E=MC2.

I said it stands for

'energy'. So, was I right?

'Energy' is the correct answer.

Energy equals 'M' for mass,

multiplied by the Constant

'C' which is the speed

of light, squared.

OK, let's recap the vocabulary

from this programme, starting

with 'equation' - a mathematical

statement using symbols to

show two equal things.

If something is called a 'bogyman',

it's something considered

bad and to be feared.

'Inscrutable' people don't show

their emotions so are very

difficult to get to know.

'Efficient' means working

quickly and effectively

in an organised way.

The verb 'to sort' means

to group together things

which share similarities.

And finally, if something

happens 'in a flash', it

happens quickly or suddenly.

That's all the time we have

to discuss algorithms. And if

you're still not 100% sure

about exactly what they are,

we hope at least you've

learned some useful vocabulary!

Join us again soon for more

trending topics, sensational

science and useful vocabulary

here at 6 Minute English from

BBC Learning English.

Bye for now!

Goodbye!